Mobile Broadcast Service (BCAST) is a kind of mobile broadband digital broadcast/multicast service. A prominent application demand of the BCAST is directional broadcast, and the directional broadcast means to broadcast for mobile users within a given location area through a mobile broadcast network, e.g. broadcast advertisement information of an shopping mall within a commercial district for users who enter the commercial district.
In the related art, in order to broadcast for the mobile users within the given location area as described above, as shown in FIG. 1 that illustrates the network composition, a content server needs to access the broadcast network corresponding to the given location area and broadcasts a broadcast message in the whole broadcast network, which makes it possible to send the broadcast message to a client within the given location area. A relation between the broadcast network and the location area is designed in advance. The broadcast network may include one base station, or several base stations, or even more base stations, and the location area corresponding to the broadcast network may cover a range covered by one base station, a range covered by several base stations or a range covered by even more base stations.
As shown in FIG. 1, content server 11a connects to broadcast networks 12a, 12b and 12c, thus content server 11a is able to directionally broadcast for location areas corresponding to the three broadcast networks above; and content server 11b connects to broadcast networks 12b and 12c, thus content server 11b is able to directionally broadcast for the location areas corresponding to the two broadcast networks 12b and 12c. FIG. 1 illustrates only the case of two content servers and three broadcast networks. In case of more content servers and more broadcast networks, a content server needs to directly connect to each of the broadcast networks which are the objects of directional broadcast.
When conducting the directional broadcast in accordance with the related art, a content server providing broadcast contents has to directly connect to the broadcast network corresponding to the location area where the directional broadcast is to be given, and one content server needs to access multiple broadcast networks when providing the broadcast contents for the multiple broadcast networks. As one-to-one connections must be created between the content servers and the broadcast networks, the network becomes much more complex, the workload of network administration for operators increases greatly, and the network security reduces.
Besides, the location area where directional broadcast is to be given must be a location area corresponding to a broadcast network designed in advance. The broadcast network may cover the range of one or several base stations, or a larger range. Thus, it may be impossible to implement a service that should be accurately directed to a smaller location area in the broadcast network.